Production of motor and jet fuels

ABSTRACT

SIMULTANEOUS PRODUCTION OF HIGH QUALITY MOTOR AND JET FUELS IS ACCOMPLISHED BY PASSING A HYDROCARBON FEED THROUGH A HYDROTREATING ZONE, REMOVING MOTOR FUEL AND JET FUEL FROM THE EFFLUENT, PASSING A FRACTION BOILING ABOVE THE JET FUEL RANGE TO A HYDROCACKING ZONE, RECOVERING FROM THE HYDROCRACKING ZONE EFFLUENT A HIGH QUALITY MOTOR FUEL AND RECYCLING THE JET FUEL AND HEAVIER FRACTION TO THE HYDROTREATING ZONE.

March 2, 1971 E. T. CHILD EIAL PRODUCTION oT MoToR AND JET FUELS Filed Feb. 29, 1968 United States Patent O 3,567,602 PRODUCTION OF MOTOR AND JET FUELS Edward T. Child, Fishkill, and Donald A. Messing, Wappingers Falls, N.Y., assignors to Texaco Inc., New

York, N.Y.

Filed Feb. 29, 1968, Ser. No. 709,484 Int. Cl. Cg 23/00 U.S. Cl. 208--89 9 Claims ABSTRACT OF THE DHSCLOSURE Simultaneous production of high quality motor and jet fuels is accomplished by passing a hydrocarbon feed through a hydrotreating zone, removing motor fuel and jet fuel from the effluent, passing a fraction boiling above the jet fuel range to a hydrocracking zone, recovering from the hydrocracking zone effluent a high quality motor fuel and recycling the jet fuel and heavier fraction to the hydrotreating zone.

This invention relates to the production of motor fuels and jet fuels. More particularly, it is concerned with the simultaneous production of high octane motor fuels and high luminometer number jet fuels by the hydrocracking of higher boiling hydrocarbon liquids.

Commercially, hydrocracking is a relatively new process in the field of petroleum refining. Known for many years as destructive hydrogenation, it was practiced without too much commercial success in Europe. However the advent of new catalysts and operating techniques has resulted in hydrocracking attaining considerable commercial significance. The process however still has some drawbacks. It is known that the presence of organic nitrogencontaining compounds and in some instances ammonia in the charge stock results in a loss of activity on the part of the hydrocracking catalyst. Although the presence of harmful nitrogen deactivants can be overcome by increasing the temperature of the reaction zone, the higher reaction temperature usually results in excessive cracking with reduced yields of naphtha and jet fuel and also results in the jet fuel having an unsatisfactory luminometer number. For the production of gasoline then, the hydrocracking should be carried out at a relatively low temperature. Recently with the increased demand for jet fuels, consideration has been given to the use of hydrocracking as a source for jet fuels. Unfortunately, the characteristics of a high luminometer number jet fuel are quite different from the characteristics of a high octane number motor fuel and accordingly it has not been possible to produce both of these products simultaneously in the same operation.

According to our invention, there is provided a process which comprises contacting a hydrocarbon oil in the presence of hydrogen with a hydrogenation catalyst under hydrogenation conditions, separating the effluent into a hydrogen-rich stream, a hydrocarbon fraction boiling below about 550 F. and a bottoms fraction, recovering a motor fuel fraction and a jet fuel fraction from the fraction boiling below about 550 F., passing the bottoms fraction with hydrogen into contact with a hydrocracking catalyst under hydrocracking conditions, separating the effluent into a hydrogen-rich stream, a hydrocarbon fraction boiling up to about 400 F. and a heavy hydrocarbon fraction having an initial boiling point of about 400 F. and returning the heavy fraction to the hydrogenation zone.

The feed to the process of the present invention may be any hydrocarbon oil having an IBP of at least 400 F. and an end point of at least about 600 F. preferably one boiling in the gas oil range, for example 400L950 F. and higher. Suitable hydrocarbon fractions include straight run 3,567,602 Patented Mar. 2, 1971 gas oil, cycle gas oil obtained from catalytic cracking, shale oil, tar sand oil, coker gas oil and the like.

The catalysts used in the hydrogenation reactor should have good hydrogenation activity but little cracking activity. Suitable catalysts comprise supported hydrogenation catalysts as for example the oxides or sulfides of cobalt, nickel, iron, molybdenum, tungsten, chromium, vanadium and mixture thereof on a support such as silica, alumina, zirconia, magnesia or zeolites not necessarily of reduced alkali metal content and mixtures thereof. Preferred catalysts comprise nickel tungsten sulfide on boria (B2O3)promoted alumina and nickel molybdenum on activated alumina. The hydrogenating component should be present in an amount between about 5% and 40% by weight based on the catalyst composition. Catalysts containing about 6% nickel and 20% tungsten or 5% nickel and 15% molybdenum has been found satisfactory.

The temperature in the hydrogenation zone may range from 60G-950 F., a preferred temperature being 650- 900 F. Space velocities or volumes of liquid feed per volume of catalyst per hour (v./v./hr.) may range from 0.1-10, but preferably are maintained within the range of 0.5-2. Hydrogen rates of SOO-10,000 s.c.f.b. may be used, a preferred rate "being 3000-75001 s.c.f.b. Preferably the pressure is maintained within the range of about 500-1500 p.s.i.g. although pressures of 10G-5000 p.s.i.g. and higher may be used.

The eiuent from the hydrogenation Zone is separated into a hydrogen-rich fraction which may be recycled directly to the hydrogenation zone or if desired may be subjected to a purication for the removal of any hydrogen sulfide and ammonia present therein. 'rhe balance of the effluent is fractionated to produce an overhead fraction boiling up to about 550 F. and a bottoms fraction boiling above 550 F. The overhead fraction may be separated into normally gaseous hydrocarbons, a light naphtha boiling up to about 235 F., a heavy naphtha fraction and a jet fuel fraction. Advantageously the heavy naphtha fraction is catalytically reformed and the reformate is combined with the light naphtha fraction to produce a naphtha of high octane number.

The 550 F.+ fraction is introduced into a hydrocracking zone `wherein it is subjected to hydrocracking conditions such as a temperature of 60G-850 F., preferably 625800 F., a space velocity from 0.1-5, a space velocity of 0.5-2 being preferred, a hydrogen rate between 1000 and 20,000 s.c.f.b. but preferably within the range of 3000-10,000 s.c.f.b. The pressure may be from 500-5000 p.s.i.g. or higher although satisfactory results are obtained at pressure between 1000 and 4000 p.s.i.g.

The hydrocracking catalysts used in the process of the present invention comprise a hydrogenating component supported on a cracking component. Suitable hydrogenating components comprise Group VIII metals or compounds thereof used alone or in combination with Group VI metals or compounds. Preferred catalysts comprise nickel, cobalt, platinum, or palladium optionally in conjunction with tungsten, molybdenum or chromium. The support is advantageously an acid acting amorphous inorganic oxide carrier such as silica, a mixture of silica and alumina or a crystalline alumino silicate zeolite of reduced alkali metal content having a uniform pore opening ranging from 6-14 angstroms either alone or in conjunction with an amorphous inorganic oxide.

llf the feed to the hydrocracking unit is low in nitrogen, for example below abou-t 15 p.p.m. based on the hydrocarbon charge, nickel oxide on silica alumina is a preferred catalyst. If, however, the charge contains higher amounts of nitrogen, then the catalyst support is preferably a zeolite of reduced alkali metal content. Suitable catalysts are palladium or nickel and tungsten on low sodium zeolite Y. A particularly suitable base of extremely low alkali metal content may be prepared by converting a sodium zeolite Y to the ammonium form by ion exchange, drying and calcining and then subjecting the resulting hydrogen form of the zeolite to additional ion exchange with an ammonium compound followed by a second drying and calcining. Such catalyst bases have an extremely low alkali metal content of about 0.1% and are eminently suitable either alone or in conjunction with amorphous silica alumina mixtures as supports for hydrocracking catalysts.

Adyantageously hydrocracking catalysts are essentially free of rare earth metals and contain less than 0.5% by weight alkali metal. Whereas the presence of rare earth metals is advantageous in cracking catalysts, it has been found that their presence is undesirable in a hydrocracking catalyst support and rare earth metal concentrations in excess of 0.2 weight percent should be avoided.

The effluent from the hydrocracking zone is separated into a hydrogen recycle stream and the normally liquid portion is separated into a light fraction boiling below about 400 F. and a 400 F.| fraction. The light fraction may be combined with the reformate and the light naphtha fraction recovered from the hydrotreater fractionator to produce a high octane gasoline. The 400 R+ fraction is recycled to the hydrotreating zone. If the charge to the hydrotreater is high in heavy aromatic hydrocarbons, i.e. containing three or more rings, the hydrogenation of the aromatic components of the recycled 400 F.{ fraction is inhibited. In such cases then it is desirable not to introduce the recycle fraction with the fresh feed into the hydrotreating zone but to introduce the recycle fraction separately into an intermediate portion of the catalyst bed thereby subjecting the fresh feed to hydrogena-tion conditions before it is brought into contact with the recycle stream.

A preferred embodiment -of the invention is described below in connection with the ow diagram of the accompanying drawing.

Hydrocarbon feed is introduced into the system through line 11 and with recycle hydrogen from line 12 enters hydrotreater 13 where it is brought into contact with a hydrotreating catalyst. Etuent from hydrotreater 13 is transferred lby means of line 14 to high pressure separator 15 from which is withdrawn a recycle hydrogen stream returned to hydrotreater 13 through lines 16, 17, 12 and 11. If desired, a bleed stream may be removed from the system through line 20. Bottoms from high pressure separator 15 pass through line 21 to fractionator 22 where a separation is made into a jet fuel and lighter fraction and a fraction heavier than jet fuel. The overhead, jet fuel and lighter fraction passes through line 24 to fractionator 25 from which a hydrocarbon gas stream is withdrawn through line 26, an IBF-235 F. stream is withdrawn through line 27, a 23S-400 F. stream is withdrawn through line 28 and jet fuel is withdrawn as product through line 29.

Bottoms from fractionator 22 is introduced by means of line 31 to hydrocracker 32 wherein it is contacted in the presence of hydrogen from line 33 with a hydrocracking catalyst and then passed through line 34 to high pressure separator 35. Hydrogen recycle is withdrawn from high pressure separator 35 through line 33 and the bottoms sent to fractionator 40 through line 41. Overhead which is cornposed of 235 F. and lighter material is Withdrawn by means of line 42 and combined with the light naphtha in line 27. The 400 Frjmaterial is recycled from fractionator 40 through lines 4S and 11 to hydrotreater 13. 1f as pointed out above the fresh feed charge to the hydrotreater is rich in heavy aromatics, e.gcontains at least 15% polynuclear aromatics, then advantageously the 400 R+ fraction is introduced into hydrotreater 13 through line 46. Otherwise it may be introduced into hydrotreater 13 through line 11 with the fresh feed.

The heavy naphtha withdrawn from fractionator 25 through line 28 is mixed with hydrogen from line 50 and introduced into catalytic reformer S1 with heavy naphtha removed from fractionator 40 through line 39. Reformer effluent passes through line 52 to high pressure separator 53 from which hydrogen is withdrawn through line 54 and portions may be recycled as necessary to hydrotreater 13 through lines 17, 12 and 11, to hydrocracker 32 through lines 55, 33 and 31 or to reformer 51 through lines 50 and 28. If desired, make-up hydrogen may be introduced into the system through line 57. Bottoms from high pressure separator are passed through lines 60 and 27 to the gasoline pool.

The following example is given for illustrative purposes only.

In this example a gas oil having the following characteristics:

API gravity 29 Boiling range, F 450-750 Sulfur, Wt. percent 0.4 Nitrogen, p.p.m. 73 Polynuclear aromatics 4volume percent 18.4

is contacted in a first stage with nickel tungsten sulfide on boria-promoted alumina containing 6% nickel, 19% tungsten, 11% boria and the balance alumina under the following conditions:

Temperature, F. 720 Pressure, p.s.i.g 1500 Space velocity, v./v./hr. 1,0 Hydrogen rate, s.c.f.b 6000 tions:

Temperature, F. 580 Pressure, p.s.i.g 1500 Space velocity, v./v./hr. 1.0

Hydrogen rate, s.c.f.b

The effluent from the hydrocracking zone is separated into a recycle hydrogen stream, a 400 F. and lighter fraction and a 400 F.{- fraction which last is recycled to an intermediate section of the hydrotreating zone. The leaded (3 cc.) Research Octane number of the 400 F. and lighter fraction is 86 and the jet fuel recovered from the hydrotreater eluent has a luminometer number of 60. If the heavy naphtha recovered from the overhead fraction of the hydrotreater fractionator is catalytically reformed and combined with the light naphtha recovered from the same overhead fraction and the mixture added to the motor fuel fraction recovered from the hydrocracker fractionator, the leaded (3 cc.) Research Octane number of the mixture is 100. However when the process is operated by separating only hydrogen from the hydrotreater eiuent and passing the balance of the ethuent to hydrocracker and motor fuel and jet fuel are recovered from the hydrocracking etiluent with recycle of the heavier than jet fuel fraction from the hydrocracker fractionator to the hydrocracker as in conventional processes the characteristics of the product recovered from the hydrocracker fractionator are Motor fuel leaded (3 cc.) Research Octane number 92 Jet fuel luminometer number 33 As the specications for K58 jet fuel are a maximum of 20 Volume percent aromatics, a minimum smoke point of 20 mm. and a minimum luminometer number of 45, it can be seen that in the operation of a conventional process the jet fuel does not meet standard specifications but that by following the procedures of our invention not only is a superior jet fuel obtained but in addition a high quality motor fuel is also produced simultaneously. Furthermore, this is accomplished by using in the hydrocracker a volume of catalyst equivalent to only 80% of the volume of the catalyst that would be used in a conventional process where all of the hydrocarbon material from the hydrotreater is charged to the hydrocracker and the material boiling above the jet fuel range in the hydrocracker eluent is recycled to the hydrocracker. In addition the motor fuel and jet fuel products are obtained in greater yield than conventional processes since these materials produced in the hydrotreater are removed from the reactant stream and therefore are not subjected to overcracking and conversion into undesirable light products in the hydrocracker.

Obviously, other modifications and variations of the invention as heerinbefore set forth may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for the production of a high octane motor fuel and the simultaneous production of a high luminometer number jet fuel which comprises contacting a hydrocarbon liquid having an initial boiling point of at least about 400 F. with a hydrotreating catalyst under hydrotreating conditions, recovering from the hydrotreater effluent a jet fuel fraction and a motor fuel fraction, and a heavy fraction boiling above the jet fuel range, contacting said heavy fraction in the presence of hydrogen with a hydrocracking catalyst under hydrocracking conditions, recovering from the hydrocracker etlluent a motor fuel fraction boiling below about 400 F. and a jet fuel and heavier fraction boiling above about 400 F., recycling the jet fuel and heavier fraction boiling above about 400 F. to the hydrotreating zone and recovering from the hydrotreater eluent with said jet fuel fraction as described above, a hydrocracked-hydrotreated jet fuel fraction.

2. The process of claim 1 in which the hydrotreater effluent is separated into a light naphtha, a heavy naphtha and a jet fuel fraction and the heavy naphtha is catalytically reformed.

3. The process of claim 2 in which the light naphtha, the reformed product and the motor fuel fraction boiling below about 400 F. are combined.

4. The process of claim 1 in which the hydrocarbon liquid contains less than 15 volume percent polycyclic aromatics and the recycle fraction is introduced into the hydrotreating zone with said liquid.

S. The process of claim 1 in which the hydrocarbon liquid contains more than 15 volume percent polycyclic aromatic and the recycle fraction is introduced into an intermediate portion of the hydrotreating zone.

6. The process of claim 1 in which a heavy naptha fraction is recovered from the hydrocracking zone eluent and is subjected to catalytic reforming.

7. The process of claim 1 in which the hydrocracking catalyst contains not more than 0.2 weight percent rare earth metals.

8. The process of claim 1 in which the hydrocracking catalyst comprises a crystalline zeolite having an alkali metal content of not more than 0.5 weight percent.

9. The process of claim 1 in which the hydrotreating catalyst comprises sulded nickel tungsten and the hydrocracking catalyst comprises nickel oxide.

References Cited UNITED STATES PATENTS 3,092,567 6/ 1963 Kozlowski et al. 208-57 3,132,087 5/ 1964 Kelley et al 20S-60 3,166,489 l/l965 Mason et al 208-57 3,239,447 3/ 1966 Reeg et al. 208-59 3,256,177 6/1966 Tulleners et al. 208-89 FOREIGN PATENTS 547,016 10/ 1957 Canada 208-60 DELBERT E. GANTZ, Primary Examiner R. BRUSKIN, Assistant Examiner 

